Impact of future urban expansion on hydroclimatology in the Upper Great Lakes Region

Global land cover/land use (LCLU) is changing notably due to expansion of urban areas. The associated reduction in infiltration and runoff lag time have long been the domain of the urban hydrologist, while this landscape transformation also leads to changes in land surface heterogeneities, resulting in alterations of land-atmosphere interactions and convective processes. The integrated impacts of both impervious area and precipitation changes have not been well-represented by existing predictive tools, which often focus at disparate scales. This on-going research project provides an integrated assessment of the multi-scale interaction of urban landcover, hydrology and convective processes, in order to quantify how urbanization has altered the hydroclimatology of urban thunderstorm events, the role of the spatial arrangement and scale of urban landcover and the impact of future land use change trajectories on urban hydrology. We integrated projected LCLUC scenarios for the period of 2005-2030 from the Land Transformation Model (LTM) for the four state region of Wisconsin, Michigan, Indiana and Illinois with the Regional Atmospheric Modeling System (RAMS). Results suggest that in some cases, urban influence created a convergence zone upstream of the urban area, resulting in precipitation increases both upstream and downstream of the urban influence. Precipitation and air temperature data from the RAMS simulations were used within the Variable Infiltration Capacity (VIC) land surface scheme, with an updated urban component, to simulate the combined impact of urbanization on various hydrologic processes and streamflow indicators. For some watersheds, the convective influence resulted in a significant increase in peak streamflow, relative to impervious influence alone.